JP2021108116A - Detection of object approached by monitoring camera - Google Patents

Abstract

To provide a method, a system and a computer program product for determining existence of an object approached a lens of a camera which monitors a scene.SOLUTION: A method activates 102 a first infrared illumination light source arranged to illuminate a scene from a first angle, and acquires 104 a first image by an image capture device. The method inactivates a first infrared illumination light source, activates 106 a second infrared illumination light source arranged to illuminate the scene from a second angle, and acquires 108 a second image by the image capture device. The method compares intensity information of the first image with intensity information of the second image to determine existence of an object approached a camera lens.SELECTED DRAWING: Figure 1

Description

The present invention relates to a camera, and more particularly to the detection of an object close to the lens of the camera.

Camera health management is becoming widespread, especially in large surveillance systems that can include hundreds or thousands of cameras for which it is virtually impossible to manually monitor the condition of each camera. One of the common problems with surveillance cameras in both indoor and outdoor environments is the attraction of spiders and insects to the infrared rays that are often incorporated into cameras.

Insects (eg butterflies, moths, etc.) and spiders, by themselves perching or approaching the lens, block the camera's field of view and reduce the camera's ability to detect events that occur in the scene it monitors. Sometimes. When an insect or spider moves across the lens or field of view, the camera's analysis software interprets this as movement in the scene rather than movement in close proximity or on the lens, triggering a false alarm. There is.

In addition, spiders in particular (and some insects) may leave "attachments" in front of the lens. An example of such an accessory is a spider web. Small insects and spiders are attracted by the camera's infrared rays and tend to leave attachments in front of the lens. When an accessory such as a spider web is illuminated by the camera light, most of the light is reflected by the accessory and returned to the camera sensor, especially when there are water droplets on the accessory, and the camera monitors until the accessory is removed. Ability is reduced to some extent. There can also be situations in which the camera is tampered with by humans for illegal purposes, for example by placing some object in close proximity to the lens to obscure the lens.

Automatically move an object close to the lens to prevent false alarms and / or to get instructions that some action (eg, obstruction removal) is needed on the camera, at least for these reasons. It is desirable to get a way to detect it.

According to the first aspect, the present invention relates to a method for determining the presence of an object close to the lens of an image capturing device that monitors a scene in a computer system. This method
-Activating the first infrared illumination light source arranged to illuminate the scene from the first angle,
-Acquiring the first image with an image capture device and
-Inactivating the first infrared illumination light source and activating the second infrared illumination light source arranged to illuminate the scene from the second angle.
-Acquiring a second image with an image capture device and
-Includes determining the presence of an object close to the lens by comparing the intensity information of the first image with the intensity information of the second image.

This method often requires no modifications to the camera's hardware setup, such as traditional cameras having illuminators that can generally be controlled to illuminate the scene from different angles. It provides a way to improve the technique for detecting objects in close proximity to. It can automatically determine if an object is close to the lens, reducing the number of false alarms and giving an appropriate alarm if any care is required for the camera. Can be generated. This method can reduce the need for manual intervention and surveillance of individual camera feeds and thus also contribute to the cost savings associated with maintaining the camera system.

According to one embodiment, the first infrared illuminating light source and the second infrared illuminating light source are arranged to illuminate an object with essentially the same intensity and wavelength. Having equal intensity and wavelength for illumination from both sides results in as similar a state as possible in terms of illumination, eliminating possible differences from illuminated objects with different reflection characteristics for different wavelengths. This also facilitates comparison of images and makes it easier to more clearly identify the differences caused by illuminating an object from purely two different angles.

According to one embodiment, the first infrared illumination light source and the second infrared illumination light source each include one or more infrared light emitting diodes. Light emitting diodes (LEDs) are a standard component in most cameras, and the use of existing components eliminates the need for major modifications to the camera hardware. The number of LEDs in each illumination source can also vary. In some cases, one LED may be sufficient for each light source, and in other cases multiple LEDs may be required for each illumination light source.

According to one embodiment, the method deactivates a second infrared illumination light source and activates a third infrared illumination light source arranged to illuminate the scene from a third angle. Acquiring the image of No. 3, comparing the intensity information of the first image, the intensity information of the second image, and the intensity information of the third image, and determining the existence of an object close to the lens. Including that further. Since more infrared illumination sources can be used than two, more images can be obtained, and paired comparisons between the three images are possible, resulting in a better determination of the presence of an object. It can be possible. As a result, the presence of an object close to the lens is more reliably determined.

According to one embodiment, this method activates / deactivates the first infrared illumination light source and the third infrared illumination light source together, and the second infrared illumination light source and the fourth infrared illumination light source. The first infrared illuminating light source and the third infrared illuminating light source are basically perpendicular to the second infrared illuminating light source and the fourth infrared illuminating light source. Have been placed. Using two groups of illumination sources that are essentially perpendicular to each other not only provides excellent illumination, but also enhances the intensity differences that can occur with objects placed close to the lens. Improves the accuracy of detecting such objects.

According to one embodiment, comparing the intensity information compensates for the overall intensity difference between the first image and the second image and determines if any local intensity difference remains. In response to a positive determination that there is a local intensity difference, it includes providing an indication of the presence of an object close to the lens. The intensity comparison is a computationally low cost comparison, and by first compensating for the overall intensity difference, the local intensity difference will appear more clearly in the image comparison, and therefore the presence of an object close to the lens. Can be easily determined.

According to one embodiment, the method compares a local intensity difference pattern with a reference intensity difference pattern and an object close to the lens when there is a match between the local intensity difference pattern and the reference intensity difference pattern. Includes providing instructions for the existence of. Having different reference intensity patterns can not only detect an object close to the lens, but can also identify what the object is, at least to some extent. For example, butterflies can result in different intensity patterns compared to spider webs, or compared to someone who tampered with the camera, and may require different types of treatment. Therefore, different types of alerts can be generated based on what is the most likely object.

According to one embodiment, the method can include assessing the local intensity difference using a neural network to determine the presence or absence of an object close to the lens. Similar to what has been described above, neural networks can be taught to automatically identify a particular object based on its intensity profile.

According to one embodiment, the method can include sending a notification to the camera engineer in response to determining that there is an object close to the lens. As mentioned above, this notification can be automatically generated based on the result of the detection. There can be different types of notifications, or different types of personnel can be notified based on what the object can be. For example, it can be more urgent to deal with a situation where a camera has been tampered with, compared to a situation where a spider web has been detected.

According to one embodiment, the object can be a spider, an insect, a spider appendage, or an insect appendage. These are some examples of various insects and "attachments" that commonly cause problems in the environment in which surveillance cameras are installed.

According to one embodiment, acquiring a first image with an image capture device and acquiring a second image with an image capture device acquires several short-term exposed images, each of which is a second. Includes combining into one image and a second image. This can be useful in situations where the scene monitored by the camera contains a lot of movement, such as when the camera overlooks the surface of the water with waves, or when the branches and leaves of trees in the background move in the wind. By adding or averaging some short-term exposed images of this type, such movements can be made uniform and objects close to the lens can be more accurately identified.

According to one embodiment, capturing the first image with an image capture device and capturing the last image with an image capture device takes several short-term exposed images, each of which is the first image. And to combine with the last image. With respect to the first and last images, you can get similar benefits to those described in the previous paragraph.

The present invention relates to a system for determining the presence of an object close to the lens of an image capture device that monitors a scene, according to a second aspect. When the memory contains instructions and the instructions are executed by the processor, the processor activates a first infrared illumination light source that is arranged to illuminate the scene from a first angle.
-Acquiring the first image with an image capture device and
-Inactivating the first infrared illumination light source and activating the second infrared illumination light source arranged to illuminate the scene from the second angle.
-Acquiring a second image with an image capture device and
A method including determining the presence of an object close to the lens by comparing the intensity information of the first image and the intensity information of the second image is performed.

The advantages of the system correspond to the advantages of the method and can vary as well.

According to a fourth aspect, the present invention relates to a computer program for determining the presence of an object close to the lens of an image capture device that monitors a scene. Computer programs
-Steps to activate the first infrared illumination light source arranged to illuminate the scene from the first angle,
-The step of acquiring the first image by the image capture device and
-The step of inactivating the first infrared illumination light source and activating the second infrared illumination light source arranged to illuminate the scene from the second angle.
-The step of acquiring a second image by the image capture device and
-Includes instructions corresponding to a step of comparing the intensity information of the first image with the intensity information of the second image to determine the presence of an object close to the lens.

Computer programs include advantages that correspond to the advantages of methods and can be varied as well.

In the accompanying drawings and description below, details of one or more embodiments of the present invention will be revealed. Other features and advantages of the present invention should become apparent from the description and drawings as well as the claims.

FIG. 5 is a flow chart showing a method 100 for determining whether or not an object close to a lens exists according to an embodiment. FIG. 5 is a flow chart showing a method 200 for determining whether or not an object close to a lens exists according to an embodiment. FIG. 5 is a schematic diagram showing an individual IR illumination light source, an image captured by a camera, and a camera 300 having image analysis components according to one embodiment.

Similar reference symbols in various drawings indicate similar elements.

As described above, one of the goals of various embodiments of the present invention is to be able to automatically detect an object close to the lens and / or some action on the camera so that false alarms can be prevented. It is to be instructed that (for example, removal of obstacles) is necessary. The present invention derives from the general principle that objects close to the lens of a camera look different, that is, they will have different intensities in the image when illuminated from different angles. Therefore, when two images are recorded by a camera and the images are captured using IR illumination from different angles, the objects in the image look different (ie, have different intensities in the acquired image). ) Will be. Therefore, it is possible to conclude whether or not there is an object close to the lens by comparing the acquired images and looking for the local intensity difference between the acquired images in particular. What is considered an "approaching" object can change depending on the particular circumstances at hand, but as a general guideline, an object "approaching" to a camera in this context is within about 0.5 meters of the camera. , Desirably within 0.2 meters of the camera lens. Appropriate alarms can be generated to address the problem in response to object detection. Next, as an example, various embodiments will be described in more detail with reference to the figures.

FIG. 1 is a flow chart showing a method 100 for determining whether or not an object exists in close proximity to a lens according to an embodiment. Method 100 can be automatically performed at various intervals as needed to efficiently detect objects placed close to the lens. As seen in FIG. 1, method 100 begins by activating a first infrared illumination source (step 102). This is schematically shown in FIG. 3, which schematically shows the surveillance camera 300 in a situation where the first infrared illumination light source 302 is activated. In general, some IR LEDs included in infrared illumination sources are common in most cameras used to monitor scenes. However, the type of illuminator that can be used with the present invention is not limited to IR LEDs, but other types of illuminators such as laser diodes can also be used.

Next, in step 104, the first image is captured. This image is schematically shown in FIG. 3 as images # 1, 304. Images are generally captured by the camera 300 using, for example, a CMOS sensor in combination with roll shutter technology, using the same type of image capture used during normal operation.

When the first image is captured, the first infrared illumination light source 302 is turned off and the second infrared illumination light source 306 is turned on (step 106). In general, the first infrared illumination light source 302 and the second infrared illumination light source 306 are on opposite sides of the lens 301 (eg, top and bottom or left and right) so that they can illuminate an object from two opposite angles. Etc.). However, it should be noted that this is not a requirement and there may be a smaller angular distance between the first infrared illumination light source 302 and the second infrared illumination light source 306. The one or more IR LEDs can also be part of both the first group 302 and the second group 306. Further, in FIG. 3, the first infrared illumination light source 302 and the second infrared illumination light source 306 are shown to be integrated in the camera 300, but are placed outside (for example, both sides) of the camera 300 itself. Note that it can also be a separate unit. The second image 308 is acquired with the second infrared illumination light source turned on, just as the first image 304 was acquired (step 108).

Finally, image analysis 310 is performed to determine if an object is present in close proximity to the lens (step 110). It should be noted that this image analysis 310 is not related to the actual depth of the object itself, but only to determine if there is an object in close proximity to the lens. This is an important advantage as depth determination generally requires considerable data processing. Since the computing resources required for various embodiments of the present invention are relatively small, it is possible to carry out the present invention even in an environment where a large computing resource cannot be used, such as a camera itself. In addition, the low computing resource requirements allow for a reduction in the overall power consumption of the camera. This is important not only to reduce heat, but also when the LEDs are used at night, as the power supply of the camera is limited by the available power according to the Ethernet standard.

In one embodiment, the image analysis 310 operates as follows. First, the overall intensity difference between the two images is calculated and compensated. Such an overall intensity difference can be due to, for example, an exposure difference or an IR LED intensity difference. This overall intensity difference is the same for all pixels in the image and can be compensated by adding the overall intensity difference to one of the images to make the overall intensity difference uniform.

Next, it is determined whether or not there is any local intensity difference pattern between the first image 304 and the second image 308. Expressed differently, it is determined between images whether the intensity in some areas is different from that in other areas. If such a local pattern is present, this is an indication of the presence of an approaching object. In some embodiments, this analysis alone may determine the presence of an approaching object. In other embodiments, this analysis can serve as an indication that a more sophisticated analysis may be required, eg, to identify the type of object, the determined local pattern is compared to the reference intensity difference pattern. NS. Based on this image analysis, alerts can be generated for users of the camera system or some maintenance team. Alternatively, the alarm can act as a trigger for an automated system, such as wipers, vibrations, noise, etc., to remove spider webs from areas close to the lens, for example. Many such variants can be envisioned by those skilled in the art.

In many cameras, a portion of the camera's housing (usually similar to a house awning protruding above a window) projects a certain distance above and / or to the side of the lens, acting as weather protection. Overall, the protrusions on this camera housing are not shown in the image captured by the lens. However, when the first and second infrared illumination sources are illuminated, the light may bounce off the protrusions, which activates the first and second illumination sources. There is a weak but stable intensity difference between the two recorded images. This difference can be addressed by activating each illumination source and recording two calibrated images in a completely dark room without an object close to the lens, and then storing these calibrated images in the camera. Later, when this camera is used to register the first and second images, each of these two calibration images is first deducted from each image before performing the image processing described above. It can be. Thus, the strength difference resulting from the configuration of the camera housing can be taken into account.

FIG. 2 is a flow chart showing a method 200 for determining whether or not an object is present in close proximity to a lens according to a different embodiment. In FIG. 2, in step 201, first, the first image is captured. When the scene is dark (eg at night), both IR illumination sources are turned on, and when the scene is bright (eg, daytime), both IR illumination sources are turned off to capture the first image. Steps 202-208 are then performed in a manner corresponding to steps 102-108 described above with reference to FIG. After acquiring the second image in step 208, the final image is acquired in step 209. This last image, like the first image, is captured with both IR illumination sources turned on or off, depending on whether the scene is dark or bright.

The image analysis in step 210 is similar to the image analysis in step 110, with one important difference. The first image captured in step 201 is compared to the last image captured in step 209, in addition to the image analysis described in step 110. If these images captured with both IR illumination sources turned on or off are different from each other, this is an indication that the scene was probably in motion during the capture of the first and second images. .. That is, any difference detected when comparing the first image and the second image is probably due to the movement in the scene captured by the camera, not due to the object actually approaching the lens. Therefore, capturing the first and last images and comparing the first and second images on both sides of the first and second image capture is a first and second image. When comparing images is actually useful, it can serve as a good additional "verification" of the obtained results.

Although the description focuses on two images and two IR illumination sources, it should be noted that the same concept can be extended to any number of images and any number of IR illumination sources. The exact choice of how many images or IR illumination sources should be used in a given situation is well within the skill of one of ordinary skill in the art.

Further, instead of capturing a single first image, a single second image, etc. as described above, in some implementations, multiple short-term exposed images are captured and then added to each other. The first image and the second image are formed respectively. This is useful in that it allows for intensity differences due to movement that should be taken into account in the image. For example, the camera may be overlooking the ocean, or trees may be moving in the wind within the camera's field of view. The effects of these types of motion can be mitigated with this type of setup, in which case several short exposure images are employed rather than a single image.

As will be appreciated by those skilled in the art, aspects of the invention can be embodied as systems, methods or computer program products. Therefore, aspects of the invention are entirely hardware embodiments, entirely software embodiments (including firmware, resident software, microcode, etc.) or combinations of software and hardware embodiments. Forms may be adopted, all of which are commonly referred to herein as "circuits," "modules," or "systems." Moreover, aspects of the invention may employ the form of a computer program product embodied in one or more computer readable media incorporating computer readable program code.

Any combination of one or more computer-readable media may be utilized. The computer-readable medium may be a computer-readable signal medium or a computer-readable storage medium. Computer-readable storage media can be, but are not limited to, for example, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices, or devices, or any suitable combination of the above. More specific examples (non-exhaustive lists) of computer-readable storage media are electrical connections with one or more wires, portable computer disksets, hard disks, random access memory (RAM), read-only memory (ROM), Includes erasable programmable read-only memory (EPROM or flash memory), fiber optics, read-only memory with portable compact disks (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the above. It will be. In the context of this document, a computer-readable storage medium is any tangible medium that can contain or store programs used by, or in connection with, a system, device, or device that executes instructions. obtain.

The propagated data signals that a computer-readable signal medium may contain embody computer-readable program code, eg, in baseband or as part of a carrier wave. Such propagated signals may employ, but are not limited to, any of a variety of forms including electromagnetic, optical, or any suitable combination thereof. A computer-readable signal medium is not a computer-readable storage medium, but any program that can communicate, propagate, or carry programs used by, or in connection with, a system, device, or device that executes instructions. Computer media may be used.

Program code incorporated into a computer-readable medium is transmitted using any suitable medium, including, but not limited to, wireless, wire, fiber optic cable, RF, etc., or any suitable combination described above. obtain. Computer program code for performing operations according to aspects of the invention includes object-oriented programming languages such as Java, Smalltalk, C ++, and conventional procedural programming languages such as the "C" programming language or similar programming languages. It may be written in any combination of one or more programming languages. The program code may be run entirely on the user's computer, partially on the user's computer, as a stand-alone software package, partially on the user's computer, partially on the remote computer, or entirely on the user's computer. It may be run on a remote computer or server. In the latter scenario, the remote computer may be connected to the user's computer through any type of network, including local area networks (LANs) or wide area networks (WANs), or (eg, through the Internet using an Internet service provider). ) May be connected to an external computer.

Aspects of the present invention will be described with reference to flow diagrams and / or block diagrams of methods, devices (systems) and computer program products according to embodiments of the present invention. Each block of the flow diagram and / or block diagram, and the combination of blocks in the flow diagram and / or block diagram can be implemented by computer program instructions. These computer program instructions are means by which instructions executed by the processor of a computer or other programmable data processing device perform a function / action specified in one or more blocks in a flow diagram and / or block diagram. Is provided to a general purpose computer, a dedicated computer, or the processor of another programmable data processing device to generate a machine.

These computer program instructions are such that the instructions stored on a computer-readable medium produce a product containing instructions that perform a function / action specified in one or more blocks in a flow diagram and / or block diagram. It can also be stored on a computer, other programmable data processor, or computer-readable medium that can instruct other devices to function in a particular way.

These computer program instructions allow instructions executed on a computer or other programmable device to provide a process for performing a function / action specified in one or more blocks in a flow diagram and / or block diagram. Can be loaded into a computer, other programmable data processor, or other device and performed on the computer to result in a series of operational steps performed on the computer, other programmable device, or other device. Create a process.

The flow diagram and block diagram in the figure illustrate the configuration, functionality, and operation of a system, method, and possible implementation of a computer program product according to various embodiments of the present invention. In this regard, each block in a flow diagram or block diagram may represent a module, segment, or portion of an instruction, which includes one or more executable instructions for performing an explicit logical function. In some alternative implementations, the features shown in the blocks may be out of the order shown in the figure. For example, two blocks shown in succession may actually be executed at substantially the same time, or sometimes in reverse order depending on the included functionality. Each block in the block diagram and / or flow diagram and the combination of blocks in the block diagram and / or flow diagram is dedicated hardware-based to perform the specified function or action or to perform a combination of dedicated hardware and computer instructions. Also note that it can be implemented by the system.

Descriptions of the various embodiments of the invention are presented for illustration purposes, but are not intended to be exhaustive or limited to disclosed embodiments. Many modifications and variations should be apparent to those skilled in the art without departing from the scope and spirit of the embodiments described. Therefore, many other variants within the scope of the claims can be envisioned by those skilled in the art.

The terminology used herein is to best describe the principles of the embodiment, the actual application or technical improvement to the technology found on the market, or is disclosed herein by those of ordinary skill in the art. It has been selected to allow understanding of these embodiments.

300 Camera 301 Lens 302 First infrared illumination light source 304 First image 306 Second infrared illumination light source 308 Second image 310 Image analysis

Claims (15)

It is a method for determining the existence of an object close to the lens (301) of the image capture device (300) that monitors the scene.
Activating a first infrared illumination light source (302) arranged to illuminate the scene from a first angle.
Acquiring the first image (304) by the image capture device (300)
Inactivating the first infrared illumination light source (302) and activating the second infrared illumination light source (306) arranged to illuminate the scene from a second angle.
Acquiring the second image (306) by the image capture device (300)
A method comprising comparing the intensity information of the first image (304) with the intensity information of the second image (306) to determine the presence of an object close to the lens (301). The method of claim 1, wherein the first infrared illumination light source (302) and the second infrared illumination light source (306) are arranged to illuminate the object with essentially the same intensity and wavelength. The method according to claim 1 or 2, wherein the first infrared illumination light source (302) and the second infrared illumination light source (306) each include one or more infrared light emitting diodes. Inactivating the second infrared illumination light source (306) and activating the third infrared illumination light source arranged to illuminate the scene from a third angle.
To get a third image and
By comparing the intensity information of the first image (304), the intensity information of the second image (308), and the intensity information of the third image, the presence of the object close to the lens is determined. The method according to any one of claims 1 to 3, further comprising determining. Activating / deactivating the first infrared illumination light source (302) and the third infrared illumination light source together, and
Further including activating / inactivating the second infrared illumination light source (306) and the fourth infrared illumination light source together.
Any of claims 1 to 3, wherein the first infrared illumination light source and the third infrared illumination light source are arranged basically perpendicular to the second infrared illumination light source and the fourth infrared illumination light source. The method described in item 1. Comparing strength information
Compensating for the overall intensity difference between the first image (304) and the second image (308), and
Determining if any local intensity difference remains and
The method of any one of claims 1-5, comprising providing an indication of the presence of an object close to the lens in response to a positive determination that there is a local intensity difference. .. Comparing the local intensity difference pattern with the reference intensity difference pattern,
The method of claim 6, further comprising providing an indication of the presence of an object close to the lens (301) when there is a match between the local intensity difference pattern and the reference intensity difference pattern. The method according to any one of claims 1 to 7, further comprising evaluating a local intensity difference using a neural network and determining the presence or absence of an object close to the lens (301). Capturing the first image before capturing the first image using both the first infrared illumination light source (302) and the second infrared illumination light source (306).
After capturing the second image using both the first infrared illumination light source (302) and the second infrared illumination light source (306), the final image is captured.
By comparing the intensity information of the first image and the intensity information of the last image to determine whether or not there is movement in the scene,
One of claims 1 to 8, further comprising verifying the determination of the presence of an object close to the lens (301) in response to the determination that there is no movement in the scene. The method described. The method according to any one of claims 1 to 9, further comprising sending a notification to the camera engineer in response to a positive determination that there is an object close to the lens (301). The method according to any one of claims 1 to 10, wherein the object is one or more of a spider, an insect, a spider appendage, and an insect appendage. Acquiring the first image (304) by the image capture device and acquiring the second image (308) by the image capture device (300) acquires some short-term exposed images. The method according to any one of claims 1 to 11, further comprising combining the short-term exposed image with the first image (304) and the second image (308), respectively. Acquiring the first image by the image capture device (300) and acquiring the last image by the image capture device (300) each obtains several short-term exposed images and the short-term. The method according to any one of claims 8 to 12, comprising combining the exposed images in between with the first image and the last image, respectively. It is a system for determining the existence of an object close to the lens (301) of the image capture device (300) that monitors the scene.
Memory and
Image capture device (300) and
The first infrared illumination light source (302) and
A second infrared illumination light source (306) and
Equipped with a processor
The memory comprises instructions, which, when executed by the processor, activate the first infrared illumination light source (302) arranged to illuminate the scene from a first angle on the processor. To do and
Acquiring the first image (304) by the image capture device (300)
Inactivating the first infrared illumination light source (302) and activating the second infrared illumination light source (306) arranged to illuminate the scene from a second angle.
Acquiring the second image (308) by the image capture device (300)
A method comprising comparing the intensity information of the first image (304) with the intensity information of the second image (308) to determine the presence of the object close to the lens (301). The system to be implemented. A computer program product for determining the presence of an object close to the lens (301) of an image capture device (300) for monitoring a scene, the computer-readable storage medium including a computer-readable storage medium incorporating program instructions. The medium itself is not a temporary signal, and the program instruction is
Activating a first infrared illumination light source (302) arranged to illuminate the scene from a first angle.
Acquiring the first image (304) by the image capture device (300)
Inactivating the first infrared illumination light source (302) and activating the second infrared illumination light source (306) arranged to illuminate the scene from a second angle.
Acquiring the second image (308) and
A method comprising comparing the intensity information of the first image (304) with the intensity information of the second image (308) to determine the presence of the object close to the lens (301). A computer program product that can be executed by a processor as it does.

Images